The present invention relates generally to tools for the handling of semiconductor wafers, chips and other articles, such as lenses, and more particularly to an ergonomically shaped vacuum-operated article pickup tool.
Vacuum operated devices for handling individual semiconductor articles are known in the art. These devices typically include a vacuum-actuated tool and a replaceable wand tip being in vacuum communication with the tool. In operation, the wand tip in association with the vacuum is used to pick up a semiconductor article.
In prior art vacuum activated devices, leakage difficulties occur in valving mechanisms employing a biased valve stem. The valve stem is biased into a position where a groove is aligned with an axial bore of the tool in communication with a vacuum source to cause displacement of an article. Fluid communication occurs between a forward and rearward passageway of the bore, when the groove is aligned with the passageways. A force, such as a user depressing a button or a lever to cause displacement of a valve stem, is used to overcome the bias and displaces the circular groove relative to the bore.
A difficulty associated with this prior art apparatus is eliminating leakage that occurs when the user desires to block off vacuum communication between the forward and rearward passageways. A misalignment of the circular groove and bore results in vacuum pressure leakage and difficulty in releasing an article from the wand tip.
U.S. Pat. No. 5,169,192 to Allison et al. describes an electronic article pickup tool used to overcome problems in the prior art associated with leakage difficulties. The patent describes a tool that ensures immediate release of an article. The vacuum-actuated electronic pickup tool includes an elongated body having a first passageway leading to a tip end of the elongated body. The tip end is brought in contact with an article that is to be picked up or released. The body includes a second passageway in fluid communication with a vacuum source and when in the open position in fluid communication with the first passageway. A third passageway links the first passageway to the atmosphere.
In one embodiment, the valve stem is biased into a normally open position by a spring so that there is fluid communication between the first and second passageways. A positive pressure seal is used to seal the third passageway from the first passageway so that the only the vacuum force is exerted on an article.
When it is desired that the article be released from the vacuum hold, the second passageway is blocked from communication with the first passageway by a sealing members fixed to a valve stem. The valve stem is attached to a button or lever that is used to overcome the bias of the spring when depressed by a user. When in the closed position, the first passageway and third passageway are in fluid communication with each other. Though U.S. Pat. No. 5,169,192 overcomes the problems of the prior art associated with leakage, it fails to provide an apparatus that is ergonomically shaped and that allows for comfortable manipulation of articles over a long period of time.
In U.S. Pat. No. 5,169,192 a button connected to a valve stem is used to overcome the bias of the spring present within the body of the apparatus. The use of the button in combination with the shape of the tool requires awkward positioning of the user""s hand and arm thus resulting in a less secure grip on the tool and discomfort to the user. Such loose gripping can result in difficulty in manipulating objects to be displaced, especially when the manipulation is to occur over long periods of time.
It is an object of the present invention to provide a vacuum-actuated tool for handling electronic articles that insures effective and immediate release of the article with comfortable and precise manipulation by a user for even extended periods of time.
The above objects have been met by a vacuum-actuated article pickup tool of the present invention. The present invention includes an elongated body having a first passageway to a tip end of the elongated body as provided in U.S. Pat. No. 5,169,192. As described in U.S. Pat. No. 5,169,192, the tip end of the elongated body is brought into contact with an article to be displaced. The elongated body includes a second passageway in fluid communication with a vacuum source. The valve stem is biased by a coil spring located beneath the stem, into a position that allows for communication between the first and second passageways. When desired, a sealing member such as an O-ring fixed to the valve stem blocks the fluid communication between the first and second passageway by to release the article. To block communication between the first and second passageways, a force is applied to a button to overcome the spring bias when it is desired that the article be released.
The present invention also includes a third passageway linking the first passageway to the atmosphere, described U.S. Pat. No. 5,169,192. From the first passageway, the passageway to the atmosphere is blocked by a second sealing member (such as an O-ring fixed to the valve stem) when it is desired that fluid communication exist between the first and second passageways. The two O-rings fixed to the valve stem are used to alternatively seal the second and third passageways from the first passageway.
The present invention utilizes two O-rings fixed to a valve stem to alternatively seal a second and third passageway from a first passageway as described in U.S. Pat. No. 5,169,192. However, the valve stem of the present invention is present at an acute angle relative to one of the axial passage ways of the tool body unlike U.S. Pat. No. 5,169,192 where the stem is perpendicularly aligned. A pivotable shell covering an upper portion of the valve stem is depressed rather than a button to overcome the spring force of the spring coil and to block the fluid communication between the first and second passageways. The pivotable shell in combination with an angled valve stem is easier to depress than the button of the prior art. Depressing a button may result in a less secure grip on the tool.
Additionally, the tool of the present invention includes an angled handle upon which the user""s arm can rest while operating the tool and a grip around which the user may wrap an index finger to get a secure hold of the tool. The use of the pivotable shell and angled valve stem in addition to the ergonomically desired shape of the apparatus permits the comfortable positioning of the user""s hand and arm thus resulting in a secure grip on the tool and comfortable positioning for the user. Such comfortable positioning results in ease in manipulating objects to be displaced, especially when the manipulation is to occur over long periods of time.